Micro-electromechanical systems (MEMS) are mechanical systems that are micromachined in silicon and may be optionally integrated with control electronic circuits. MEMS are generally categorized as either microsensor or microactuator systems, depending on the application. MEMS incorporate electrostatic, electromagnetic, thermoelastic, piezoelectric, or piezoresistive effects in the operations of the systems.
One use for MEMS devices is in drop on demand inkjet technology that has been employed in commercial products, such as printers, plotters, and facsimile machines. Generally, an inkjet image is formed by the selective activation of inkjets within a printhead to eject ink onto an ink receiving member. To facilitate manufacture of an inkjet array printhead, an array of inkjet ejectors can be formed from multiple laminated plates or sheets. These sheets are configured with arrays of ink droplet ejectors. Each ejector may include structures such as an actuator, pressure chamber, outlet, and aperture nozzle. These structures are formed from the superposition of the multiple laminated structural layers. An example of a laminated layer inkjet array for a printhead includes a silicon layer bonded to an aperture layer formed on a polymer material, such as polyimide or thermoplastic. The silicon layer includes an array of actuators. Each actuator has an associated ink inlet, diaphragm, and pressure chamber area. The polymer aperture layer includes an aperture in the form of a nozzle. Walls are formed on the silicon layer to for a pressure chamber for each operator and the polymer aperture layer is bonded to the walls to enclose the pressure chamber and establish fluid communication between each aperture in the aperture layer and each pressure chamber formed on the silicon layer. Once formed, each actuator in the array of actuators may be selectively activated to deform the diaphragm and expel an ink droplet from the pressure chamber through the aperture.
The process for bonding the polymer aperture plate to the walls extending from the silicon layer requires alignment of the apertures in the aperture layer with the silicon layer. Existing manufacturing processes produce actuator arrays by forming a plurality of actuator arrays on a silicon wafer and then cutting the silicon wafer to separate the actuator arrays from one another. The inlets, diaphragms, and walls are then formed on the actuator arrays and the polymer aperture plate is bonded to the walls extending from the silicon plate. Known methods of aligning apertures in an aperture plate to actuators and their associated structure on the silicon layer often result in alignment errors of at least five microns in magnitude. Increased efficiencies and improved precision in alignment in the manufacture of the MEMS printheads would be beneficial to the fields of imaging in general, and inkjet printing in particular.